1. Field of the Invention
The present invention relates to an image sensor, and more particularly to an image sensor comprising a flexible printed circuit board.
2. Description of the Background Art
An image sensor comprising a flexible printed circuit board is known in general, as disclosed in each of Japanese Patent Laying-Open Nos. 8-116140, 2005-302879 and 2007-43129, for example.
The aforementioned Japanese Patent Laying-Open No. 8-116140 discloses a flexible printed circuit board, in which a prescribed wiring is formed on an upper surface of a base film, copper foil is provided on an overall lower surface of the base film, and the copper foil only on a portion to be folded (folded portion) is thereafter removed. This flexible printed circuit board can be easily folded on the folded portion provided with no copper foil by applying folding stress from both ends of the flexible printed circuit board.
The aforementioned Japanese Patent Laying-Open No. 2005-302879 discloses a flexible printed circuit board including a deformable insulating substrate having a wiring pattern made of copper on at least a first surface and a reinforcing conductive layer which is made of metal softer than copper and provided on an overall region of a repeatedly folded portion in the wiring pattern. In this flexible printed circuit board, stress by folding is dispersed in the reinforcing conductive layer and a conductive path is compensated by the reinforcing conductive layer also when the wiring pattern is disconnected.
The aforementioned Japanese Patent Laying-Open No. 2007-43129 discloses an image sensor comprising an imaging element, a movable moving member (movable member), a movable flexible printed circuit board fixed on a fixed member (circuit board) and having looseness (extension/contraction region) held between folded portions, in which a slit is provided parallel to a direction of movement of the flexible printed circuit board on the flexible printed circuit board. In this image sensor, load resistance caused by deformation of the flexible printed circuit board can be reduced by the slit even when looseness is small, and hence a camera shake correction function and an image sensor having the camera shake correction function can be downsized and reduce power consumption.
In the flexible printed circuit board described in the aforementioned Japanese Patent Laying-Open No. 8-116140, however, only the wiring can be visually recognized from a side of the upper surface and the folded portion can not be visually recognized from the side of the upper surface, and hence it is conceivable that the flexible printed circuit board is disadvantageously folded at an undesirable folded position or angle. Thus, when an extension/contraction region is provided by folding the flexible printed circuit board, the extension/contraction region of the flexible printed circuit board is not properly provided and hence a movable region of the flexible printed circuit board is not properly ensured. Consequently, it is conceivable that camera shake correction is not disadvantageously properly performed in the image sensor comprising the flexible printed circuit board.
In the flexible printed circuit board described in the aforementioned Japanese Patent Laying-Open No. 2005-302879, the reinforcing conductive layer are provided on the overall region of the folded portion and the extension/contraction region of the flexible printed circuit board when the extension/contraction region is provided by folding the flexible printed circuit board. Thus, it is difficult to visually distinguish between the extension/contraction region and the folded portion, and hence it is conceivable that the flexible printed circuit board is disadvantageously folded at an undesirable folded position or angle. Thus, the extension/contraction region of the flexible printed circuit board is not properly provided and hence a movable region of the flexible printed circuit board is not properly ensured. Consequently, it is conceivable that camera shake correction is not disadvantageously properly performed in the image sensor comprising the flexible printed circuit board.
In the image sensor described in the aforementioned Japanese Patent Laying-Open No. 2007-43129, no component is provided at a folded position of the flexible printed circuit board and the folded position can not be visually recognized, and hence and hence it is conceivable that the flexible printed circuit board is disadvantageously folded at an undesirable folded position or angle. Thus, the extension/contraction region of the flexible printed circuit board is not properly provided and hence a movable region of the flexible printed circuit board is not properly ensured. Consequently, it is conceivable that camera shake correction is not disadvantageously properly performed in the image sensor comprising the flexible printed circuit board.